Fish tanks for home or office use have evolved through the years from a small circular fish bowl with a few goldfish to large glass or plastic tanks capable of holding 20 to 50 or more gallons of water. Larger tanks, of course, allow larger fish and more elaborate surroundings. The larger volume of water, however, presents some significant structural problems in that a 50 gallon tank must carry a load of over 300 pounds of water. The walls of glass or plastic must be of sufficient strength to support the load, that is, they must be a quarter inch or more in thickness, adding again to the overall weight. Going to larger fish tanks usually of a rectangular shape, the structure necessary to provide the tank with adequate security against leakage or breakage presents a heavy structure and one which is disproportionally expensive for the function provided.
In addition to the foregoing limitations the large fish tanks, when empty, are difficult to transport and store safely, adding more to their expense.
Attractive as they are, large fish tanks usually present a totally artificial appearance of the fishes environment.